Pure intraoperative MEP losses: Assessment of neuro-logical and neuroradiological postoperative outcome

Introduction: In supratentorial surgery, the cortical depth of excitation of the pyramidal neurons by transcranial electric stimulation (TES) is critical to detect even most superficial cortical lesions affecting the motor cortex. An excitation caudally to a lesion consequences false negative results. Exclusive (i.e. no changes in other modalities as SEPs) mMEP changes were correlated to clinical and neuroradiological outcome to evaluate their significance. Methods: MMEPs (all elicited with TES; in 14 patients also direct cortical stimulation) were elicited with a train of 5 anodal rectangular pulses (0.5ms puls…